Several arrangements of the type described above are already known.
For the removal of objects made of magnetisable material such as metal shavings, rust flakes and the like from liquids, e.g. heat exchangers in steam boilers and in lubrication systems, the method is already known of using bodies contained in the liquid in the form of plugs made of permanent magnetic material. Here the plugs are so arranged that they project slightly into the flow path of the liquid, or are in a sump, and here create a magnetic field which attracts the magnetisable foreign bodies. Otherwise these would be entrained by the liquid in the liquid flow. Also other arrangements for this purpose are already known.
Thus mention can be made of the fact that by virtue of U.S. Pat. No. 2,798,611 the method is already known of providing two permanent magnets to the underside of an attraction surface and to locate both these magnets in a container.
In German patent specification as filed No. 1 012 87l the method is already known of utilising a number of bodies which distribute the magnetic field in the liquid and which interact with an electromagnet so that the liquid flows through and past a number of magnetisable discs. Here the electromagnetic unit forms one section whilst the container for cleaning the liquid forms the second section, the sections interacting with each other.
The method is already known from British patent specification No. 1 311 794 of cleaning liquid by allowing the liquid to traverse a narrow gap in connection with a strong magnetic field.
Finally it could be mentioned that arrangements of the relevant type are illustrated and described in Danish patent specification No. 82 001, U.S. Pat. No. 1,673,837 and Swedish patent specification No. 111 582.